There’s a neat video going around of a hunting strategy pursued by bottle-nosed dolphins in shallow waters. They swim in tightening circles and use their tails to make fences of cloudy water to trap schools of fish:
Very cool. But at the end of it good Mr. Attenborough pronounces that dolphins are the only known species to pursue this fishing technique. Yet right there in the related videos panel is an even more dramatic video of humpback whales using air bubbles to do essentially the same thing in deep water.
I wonder how widely known the “schooling fish are afraid to swim through churned up water” behavior is among ocean mammals.